Mean Fractional Error

Compute the Mean Fractional Error (MFE) of observed and predicted data.

Usage

mfe(obs, pred, use = "everything")

Arguments

obs

A numeric vector, data.frame or data.table with observation data.

pred

A numeric vector, data.frame or data.table with model (predicted) data.

use

An optional character vector giving a method for computing MFE in the presence of missing values. This must be either everything or complete.obs.

Value

The mean fractional error of input data as a numeric.

Details

The function computes the Mean Fractional Error (MFE) according to EPA formulation: $$ \mathrm{MFE} = 100 \cdot \sum_{i=1}^{N} \left( \frac{|P_i - O_i|}{0.5(P_i + O_i)} \right) $$

The MFE thus normalizes the error for each model-observed pair by the average of the model and observation before taking the average.

Examples

if (FALSE) {
validationData[, .(mfe = mfe(obs, mod, use = "complete.obs"))]
}